| 1 | /* |
| 2 | * Copyright © 2010 Intel Corporation |
| 3 | * Copyright © 2010 Francisco Jerez <currojerez@riseup.net> |
| 4 | * |
| 5 | * Permission is hereby granted, free of charge, to any person obtaining a |
| 6 | * copy of this software and associated documentation files (the "Software"), |
| 7 | * to deal in the Software without restriction, including without limitation |
| 8 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| 9 | * and/or sell copies of the Software, and to permit persons to whom the |
| 10 | * Software is furnished to do so, subject to the following conditions: |
| 11 | * |
| 12 | * The above copyright notice and this permission notice (including the next |
| 13 | * paragraph) shall be included in all copies or substantial portions of the |
| 14 | * Software. |
| 15 | * |
| 16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| 21 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| 22 | * IN THE SOFTWARE. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | #ifndef _XORG_LIST_H_ |
| 27 | #define _XORG_LIST_H_ |
| 28 | |
| 29 | #include <stddef.h> /* offsetof() */ |
| 30 | |
| 31 | /** |
| 32 | * @file Classic doubly-link circular list implementation. |
| 33 | * For real usage examples of the linked list, see the file test/list.c |
| 34 | * |
| 35 | * Example: |
| 36 | * We need to keep a list of struct foo in the parent struct bar, i.e. what |
| 37 | * we want is something like this. |
| 38 | * |
| 39 | * struct bar { |
| 40 | * ... |
| 41 | * struct foo *list_of_foos; -----> struct foo {}, struct foo {}, struct foo{} |
| 42 | * ... |
| 43 | * } |
| 44 | * |
| 45 | * We need one list head in bar and a list element in all list_of_foos (both are of |
| 46 | * data type 'struct xorg_list'). |
| 47 | * |
| 48 | * struct bar { |
| 49 | * ... |
| 50 | * struct xorg_list list_of_foos; |
| 51 | * ... |
| 52 | * } |
| 53 | * |
| 54 | * struct foo { |
| 55 | * ... |
| 56 | * struct xorg_list entry; |
| 57 | * ... |
| 58 | * } |
| 59 | * |
| 60 | * Now we initialize the list head: |
| 61 | * |
| 62 | * struct bar bar; |
| 63 | * ... |
| 64 | * xorg_list_init(&bar.list_of_foos); |
| 65 | * |
| 66 | * Then we create the first element and add it to this list: |
| 67 | * |
| 68 | * struct foo *foo = malloc(...); |
| 69 | * .... |
| 70 | * xorg_list_add(&foo->entry, &bar.list_of_foos); |
| 71 | * |
| 72 | * Repeat the above for each element you want to add to the list. Deleting |
| 73 | * works with the element itself. |
| 74 | * xorg_list_del(&foo->entry); |
| 75 | * free(foo); |
| 76 | * |
| 77 | * Note: calling xorg_list_del(&bar.list_of_foos) will set bar.list_of_foos to an empty |
| 78 | * list again. |
| 79 | * |
| 80 | * Looping through the list requires a 'struct foo' as iterator and the |
| 81 | * name of the field the subnodes use. |
| 82 | * |
| 83 | * struct foo *iterator; |
| 84 | * xorg_list_for_each_entry(iterator, &bar.list_of_foos, entry) { |
| 85 | * if (iterator->something == ...) |
| 86 | * ... |
| 87 | * } |
| 88 | * |
| 89 | * Note: You must not call xorg_list_del() on the iterator if you continue the |
| 90 | * loop. You need to run the safe for-each loop instead: |
| 91 | * |
| 92 | * struct foo *iterator, *next; |
| 93 | * xorg_list_for_each_entry_safe(iterator, next, &bar.list_of_foos, entry) { |
| 94 | * if (...) |
| 95 | * xorg_list_del(&iterator->entry); |
| 96 | * } |
| 97 | * |
| 98 | */ |
| 99 | |
| 100 | /** |
| 101 | * The linkage struct for list nodes. This struct must be part of your |
| 102 | * to-be-linked struct. struct xorg_list is required for both the head of the |
| 103 | * list and for each list node. |
| 104 | * |
| 105 | * Position and name of the struct xorg_list field is irrelevant. |
| 106 | * There are no requirements that elements of a list are of the same type. |
| 107 | * There are no requirements for a list head, any struct xorg_list can be a list |
| 108 | * head. |
| 109 | */ |
| 110 | struct xorg_list { |
| 111 | struct xorg_list *next, *prev; |
| 112 | }; |
| 113 | |
| 114 | /** |
| 115 | * Initialize the list as an empty list. |
| 116 | * |
| 117 | * Example: |
| 118 | * xorg_list_init(&bar->list_of_foos); |
| 119 | * |
| 120 | * @param The list to initialized. |
| 121 | */ |
| 122 | static inline void |
| 123 | xorg_list_init(struct xorg_list *list) |
| 124 | { |
| 125 | list->next = list->prev = list; |
| 126 | } |
| 127 | |
| 128 | static inline void |
| 129 | __xorg_list_add(struct xorg_list *entry, |
| 130 | struct xorg_list *prev, struct xorg_list *next) |
| 131 | { |
| 132 | next->prev = entry; |
| 133 | entry->next = next; |
| 134 | entry->prev = prev; |
| 135 | prev->next = entry; |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Insert a new element after the given list head. The new element does not |
| 140 | * need to be initialised as empty list. |
| 141 | * The list changes from: |
| 142 | * head → some element → ... |
| 143 | * to |
| 144 | * head → new element → older element → ... |
| 145 | * |
| 146 | * Example: |
| 147 | * struct foo *newfoo = malloc(...); |
| 148 | * xorg_list_add(&newfoo->entry, &bar->list_of_foos); |
| 149 | * |
| 150 | * @param entry The new element to prepend to the list. |
| 151 | * @param head The existing list. |
| 152 | */ |
| 153 | static inline void |
| 154 | xorg_list_add(struct xorg_list *entry, struct xorg_list *head) |
| 155 | { |
| 156 | __xorg_list_add(entry, head, head->next); |
| 157 | } |
| 158 | |
| 159 | /** |
| 160 | * Append a new element to the end of the list given with this list head. |
| 161 | * |
| 162 | * The list changes from: |
| 163 | * head → some element → ... → lastelement |
| 164 | * to |
| 165 | * head → some element → ... → lastelement → new element |
| 166 | * |
| 167 | * Example: |
| 168 | * struct foo *newfoo = malloc(...); |
| 169 | * xorg_list_append(&newfoo->entry, &bar->list_of_foos); |
| 170 | * |
| 171 | * @param entry The new element to prepend to the list. |
| 172 | * @param head The existing list. |
| 173 | */ |
| 174 | static inline void |
| 175 | xorg_list_append(struct xorg_list *entry, struct xorg_list *head) |
| 176 | { |
| 177 | __xorg_list_add(entry, head->prev, head); |
| 178 | } |
| 179 | |
| 180 | static inline void |
| 181 | __xorg_list_del(struct xorg_list *prev, struct xorg_list *next) |
| 182 | { |
| 183 | next->prev = prev; |
| 184 | prev->next = next; |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Remove the element from the list it is in. Using this function will reset |
| 189 | * the pointers to/from this element so it is removed from the list. It does |
| 190 | * NOT free the element itself or manipulate it otherwise. |
| 191 | * |
| 192 | * Using xorg_list_del on a pure list head (like in the example at the top of |
| 193 | * this file) will NOT remove the first element from |
| 194 | * the list but rather reset the list as empty list. |
| 195 | * |
| 196 | * Example: |
| 197 | * xorg_list_del(&foo->entry); |
| 198 | * |
| 199 | * @param entry The element to remove. |
| 200 | */ |
| 201 | static inline void |
| 202 | xorg_list_del(struct xorg_list *entry) |
| 203 | { |
| 204 | __xorg_list_del(entry->prev, entry->next); |
| 205 | xorg_list_init(entry); |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Check if the list is empty. |
| 210 | * |
| 211 | * Example: |
| 212 | * xorg_list_is_empty(&bar->list_of_foos); |
| 213 | * |
| 214 | * @return True if the list contains one or more elements or False otherwise. |
| 215 | */ |
| 216 | static inline int |
| 217 | xorg_list_is_empty(struct xorg_list *head) |
| 218 | { |
| 219 | return head->next == head; |
| 220 | } |
| 221 | |
| 222 | /** |
| 223 | * Returns a pointer to the container of this list element. |
| 224 | * |
| 225 | * Example: |
| 226 | * struct foo* f; |
| 227 | * f = container_of(&foo->entry, struct foo, entry); |
| 228 | * assert(f == foo); |
| 229 | * |
| 230 | * @param ptr Pointer to the struct xorg_list. |
| 231 | * @param type Data type of the list element. |
| 232 | * @param member Member name of the struct xorg_list field in the list element. |
| 233 | * @return A pointer to the data struct containing the list head. |
| 234 | */ |
| 235 | #ifndef container_of |
| 236 | #define container_of(ptr, type, member) \ |
| 237 | (type *)((char *)(ptr) - offsetof(type, member)) |
| 238 | #endif |
| 239 | |
| 240 | /** |
| 241 | * Alias of container_of |
| 242 | */ |
| 243 | #define xorg_list_entry(ptr, type, member) \ |
| 244 | container_of(ptr, type, member) |
| 245 | |
| 246 | /** |
| 247 | * Retrieve the first list entry for the given list pointer. |
| 248 | * |
| 249 | * Example: |
| 250 | * struct foo *first; |
| 251 | * first = xorg_list_first_entry(&bar->list_of_foos, struct foo, list_of_foos); |
| 252 | * |
| 253 | * @param ptr The list head |
| 254 | * @param type Data type of the list element to retrieve |
| 255 | * @param member Member name of the struct xorg_list field in the list element. |
| 256 | * @return A pointer to the first list element. |
| 257 | */ |
| 258 | #define xorg_list_first_entry(ptr, type, member) \ |
| 259 | xorg_list_entry((ptr)->next, type, member) |
| 260 | |
| 261 | /** |
| 262 | * Retrieve the last list entry for the given listpointer. |
| 263 | * |
| 264 | * Example: |
| 265 | * struct foo *first; |
| 266 | * first = xorg_list_last_entry(&bar->list_of_foos, struct foo, list_of_foos); |
| 267 | * |
| 268 | * @param ptr The list head |
| 269 | * @param type Data type of the list element to retrieve |
| 270 | * @param member Member name of the struct xorg_list field in the list element. |
| 271 | * @return A pointer to the last list element. |
| 272 | */ |
| 273 | #define xorg_list_last_entry(ptr, type, member) \ |
| 274 | xorg_list_entry((ptr)->prev, type, member) |
| 275 | |
| 276 | #ifdef HAVE_TYPEOF |
| 277 | #define __container_of(ptr, sample, member) \ |
| 278 | container_of(ptr, typeof(*sample), member) |
| 279 | #else |
| 280 | /* This implementation of __container_of has undefined behavior according |
| 281 | * to the C standard, but it works in many cases. If your compiler doesn't |
| 282 | * support typeof() and fails with this implementation, please try a newer |
| 283 | * compiler. |
| 284 | */ |
| 285 | #define __container_of(ptr, sample, member) \ |
| 286 | (void *)((char *)(ptr) \ |
| 287 | - ((char *)&(sample)->member - (char *)(sample))) |
| 288 | #endif |
| 289 | |
| 290 | /** |
| 291 | * Loop through the list given by head and set pos to struct in the list. |
| 292 | * |
| 293 | * Example: |
| 294 | * struct foo *iterator; |
| 295 | * xorg_list_for_each_entry(iterator, &bar->list_of_foos, entry) { |
| 296 | * [modify iterator] |
| 297 | * } |
| 298 | * |
| 299 | * This macro is not safe for node deletion. Use xorg_list_for_each_entry_safe |
| 300 | * instead. |
| 301 | * |
| 302 | * @param pos Iterator variable of the type of the list elements. |
| 303 | * @param head List head |
| 304 | * @param member Member name of the struct xorg_list in the list elements. |
| 305 | * |
| 306 | */ |
| 307 | #define xorg_list_for_each_entry(pos, head, member) \ |
| 308 | for (pos = __container_of((head)->next, pos, member); \ |
| 309 | &pos->member != (head); \ |
| 310 | pos = __container_of(pos->member.next, pos, member)) |
| 311 | |
| 312 | /** |
| 313 | * Loop through the list, keeping a backup pointer to the element. This |
| 314 | * macro allows for the deletion of a list element while looping through the |
| 315 | * list. |
| 316 | * |
| 317 | * See xorg_list_for_each_entry for more details. |
| 318 | */ |
| 319 | #define xorg_list_for_each_entry_safe(pos, tmp, head, member) \ |
| 320 | for (pos = __container_of((head)->next, pos, member), \ |
| 321 | tmp = __container_of(pos->member.next, pos, member); \ |
| 322 | &pos->member != (head); \ |
| 323 | pos = tmp, tmp = __container_of(pos->member.next, tmp, member)) |
| 324 | |
| 325 | /* NULL-Terminated List Interface |
| 326 | * |
| 327 | * The interface below does _not_ use the struct xorg_list as described above. |
| 328 | * It is mainly for legacy structures that cannot easily be switched to |
| 329 | * struct xorg_list. |
| 330 | * |
| 331 | * This interface is for structs like |
| 332 | * struct foo { |
| 333 | * [...] |
| 334 | * struct foo *next; |
| 335 | * [...] |
| 336 | * }; |
| 337 | * |
| 338 | * The position and field name of "next" are arbitrary. |
| 339 | */ |
| 340 | |
| 341 | /** |
| 342 | * Init the element as null-terminated list. |
| 343 | * |
| 344 | * Example: |
| 345 | * struct foo *list = malloc(); |
| 346 | * nt_list_init(list, next); |
| 347 | * |
| 348 | * @param list The list element that will be the start of the list |
| 349 | * @param member Member name of the field pointing to next struct |
| 350 | */ |
| 351 | #define nt_list_init(_list, _member) \ |
| 352 | (_list)->_member = NULL |
| 353 | |
| 354 | /** |
| 355 | * Returns the next element in the list or NULL on termination. |
| 356 | * |
| 357 | * Example: |
| 358 | * struct foo *element = list; |
| 359 | * while ((element = nt_list_next(element, next)) { } |
| 360 | * |
| 361 | * This macro is not safe for node deletion. Use nt_list_for_each_entry_safe |
| 362 | * instead. |
| 363 | * |
| 364 | * @param list The list or current element. |
| 365 | * @param member Member name of the field pointing to next struct. |
| 366 | */ |
| 367 | #define nt_list_next(_list, _member) \ |
| 368 | (_list)->_member |
| 369 | |
| 370 | /** |
| 371 | * Iterate through each element in the list. |
| 372 | * |
| 373 | * Example: |
| 374 | * struct foo *iterator; |
| 375 | * nt_list_for_each_entry(iterator, list, next) { |
| 376 | * [modify iterator] |
| 377 | * } |
| 378 | * |
| 379 | * @param entry Assigned to the current list element |
| 380 | * @param list The list to iterate through. |
| 381 | * @param member Member name of the field pointing to next struct. |
| 382 | */ |
| 383 | #define nt_list_for_each_entry(_entry, _list, _member) \ |
| 384 | for (_entry = _list; _entry; _entry = (_entry)->_member) |
| 385 | |
| 386 | /** |
| 387 | * Iterate through each element in the list, keeping a backup pointer to the |
| 388 | * element. This macro allows for the deletion of a list element while |
| 389 | * looping through the list. |
| 390 | * |
| 391 | * See nt_list_for_each_entry for more details. |
| 392 | * |
| 393 | * @param entry Assigned to the current list element |
| 394 | * @param tmp The pointer to the next element |
| 395 | * @param list The list to iterate through. |
| 396 | * @param member Member name of the field pointing to next struct. |
| 397 | */ |
| 398 | #define nt_list_for_each_entry_safe(_entry, _tmp, _list, _member) \ |
| 399 | for (_entry = _list, _tmp = (_entry) ? (_entry)->_member : NULL;\ |
| 400 | _entry; \ |
| 401 | _entry = _tmp, _tmp = (_tmp) ? (_tmp)->_member: NULL) |
| 402 | |
| 403 | /** |
| 404 | * Append the element to the end of the list. This macro may be used to |
| 405 | * merge two lists. |
| 406 | * |
| 407 | * Example: |
| 408 | * struct foo *elem = malloc(...); |
| 409 | * nt_list_init(elem, next) |
| 410 | * nt_list_append(elem, list, struct foo, next); |
| 411 | * |
| 412 | * Resulting list order: |
| 413 | * list_item_0 -> list_item_1 -> ... -> elem_item_0 -> elem_item_1 ... |
| 414 | * |
| 415 | * @param entry An entry (or list) to append to the list |
| 416 | * @param list The list to append to. This list must be a valid list, not |
| 417 | * NULL. |
| 418 | * @param type The list type |
| 419 | * @param member Member name of the field pointing to next struct |
| 420 | */ |
| 421 | #define nt_list_append(_entry, _list, _type, _member) \ |
| 422 | do { \ |
| 423 | _type *__iterator = _list; \ |
| 424 | while (__iterator->_member) { __iterator = __iterator->_member;}\ |
| 425 | __iterator->_member = _entry; \ |
| 426 | } while (0) |
| 427 | |
| 428 | /** |
| 429 | * Insert the element at the next position in the list. This macro may be |
| 430 | * used to insert a list into a list. |
| 431 | * |
| 432 | * struct foo *elem = malloc(...); |
| 433 | * nt_list_init(elem, next) |
| 434 | * nt_list_insert(elem, list, struct foo, next); |
| 435 | * |
| 436 | * Resulting list order: |
| 437 | * list_item_0 -> elem_item_0 -> elem_item_1 ... -> list_item_1 -> ... |
| 438 | * |
| 439 | * @param entry An entry (or list) to append to the list |
| 440 | * @param list The list to insert to. This list must be a valid list, not |
| 441 | * NULL. |
| 442 | * @param type The list type |
| 443 | * @param member Member name of the field pointing to next struct |
| 444 | */ |
| 445 | #define nt_list_insert(_entry, _list, _type, _member) \ |
| 446 | do { \ |
| 447 | nt_list_append((_list)->_member, _entry, _type, _member); \ |
| 448 | (_list)->_member = _entry; \ |
| 449 | } while (0) |
| 450 | |
| 451 | /** |
| 452 | * Delete the entry from the list by iterating through the list and |
| 453 | * removing any reference from the list to the entry. |
| 454 | * |
| 455 | * Example: |
| 456 | * struct foo *elem = <assign to right element> |
| 457 | * nt_list_del(elem, list, struct foo, next); |
| 458 | * |
| 459 | * @param entry The entry to delete from the list. entry is always |
| 460 | * re-initialized as a null-terminated list. |
| 461 | * @param list The list containing the entry, set to the new list without |
| 462 | * the removed entry. |
| 463 | * @param type The list type |
| 464 | * @param member Member name of the field pointing to the next entry |
| 465 | */ |
| 466 | #define nt_list_del(_entry, _list, _type, _member) \ |
| 467 | do { \ |
| 468 | _type *__e = _entry; \ |
| 469 | if (__e == NULL || _list == NULL) break; \ |
| 470 | if ((_list) == __e) { \ |
| 471 | _list = __e->_member; \ |
| 472 | } else { \ |
| 473 | _type *__prev = _list; \ |
| 474 | while (__prev->_member && __prev->_member != __e) \ |
| 475 | __prev = nt_list_next(__prev, _member); \ |
| 476 | if (__prev->_member) \ |
| 477 | __prev->_member = __e->_member; \ |
| 478 | } \ |
| 479 | nt_list_init(__e, _member); \ |
| 480 | } while(0) |
| 481 | |
| 482 | /** |
| 483 | * DO NOT USE THIS. |
| 484 | * This is a remainder of the xfree86 DDX attempt of having a set of generic |
| 485 | * list functions. Unfortunately, the xf86OptionRec uses it and we can't |
| 486 | * easily get rid of it. Do not use for new code. |
| 487 | */ |
| 488 | typedef struct generic_list_rec { |
| 489 | void *next; |
| 490 | } GenericListRec, *GenericListPtr, *glp; |
| 491 | |
| 492 | #endif |